Try this formula as a sample then use it to suit yourself. Ideal to use with a fairisle pattern, any card can be used, but experiment to find the best kind. Start with a card which has about 40 rows to the pattern

Adults jersey in 4 ply, adjust length at * for childs garmentKnit sleeves first to *30 rows above armhole in raglan, run off onto waste yarnKnit back to *30 rows above armhole, doing short row knitting to form a slight dip in the middle, leave knitting on the machine.Add sleeves each side, picking up sts to the centre of sleeves only, leave waste yarn on. (Add 1 st extra each end by including heel of last st)Knit 2 rows over all needles and select 1 st row for fairisle. When back is complete, work front to match.

Would convert to decreasing for top of beanies very well if you start at every 8 th needle and reduce the number of rows in between. (marked with *) Lines do show if you use acrylic yarn but they are not unsightly. If knitting with wool, lines seem to disappear after washing.